What spec are you building the cage to Dan ?
Drag racing! This cage will be good for 9.99 seconds or quicker (down to 8.5 I believe) if I have the correct requirements elsewhere in the car which I wont as I dont realy ever intend running that quick - but it's there if I do.
Everything on the car will be spec'd for down to a 10 second car:
10.99 1/4-mile (6.99 1/8-mile) or quicker:
-5-point roll bar is still okay to 10.00 1/4-mile (6.40 1/8-mile) in hardtop / t-top with un-altered floors, firewall and frame rails (wheel tubs are okay). If the floor and/or firewall has been modified, then a full roll cage is required beginning at a 10.99 e.t. or any vehicle running 135 mph or faster (regardless of e.t.). The roll cage must be constructed of a minimum o.d. mild steel or chrome moly tubing (moly can be a smaller o.d and is lighter but more expensive), see diagram below for specs. Roll cage must be padded anywhere the driver's helmet may contact it while in the driving position, see diagram below for specs.
-Convertibles require full roll cage at 10.99 and quicker.
See diagram below.
-aftermarket axles with positive retention (c-clip eliminators)
-Transmission shield SFI Spec 4.1 at 10.99 and quicker or 135 mph and quicker (blanket is okay, no expiration date)
-Harmonic Balancer SFI Spec 18.1 (no expiration date)
Not sure how I get around the aftermarket axles - I already will have non genuine but I will need to look in to it a bit more! Wont be competitively racign for soem time yet though!
The cage should also pass most FIA regulations too I think.